https://github.com/zserge/fenster
This library provides the most minimal and highly opinionated way to display a cross-platform 2D canvas. If you remember Borland BGI or drawing things in QBASIC or INT 10h - you know what I mean. As a nice bonus you also get cross-platform keyboard/mouse input and audio playback in only a few lines of code.
The concept reminds me the MGRX library (and others, actually). This one is really bare-bones though. However the minimal implementation (and in a single header file, plus a second one for sound) has its advantages. I played a bit with it and I liked the simplicity and how easily it lets you get going. Still, if you need anything but the very basics, you have to implement it yourself. This might be a good or a bad thing, depending on your point of view. Personally, I would like it to have a little more, but not much.
The code itself is “clean”, and doesn’t try to do, you know, all those crazy things C lets you do (shooting your own feet in the process). This is a big fat plus for Fenster. It also means it should be easily bindable to my preferred programming language (or any other programming language) without much hassle.